JPS6338043A - Starting clutch controlling method for automatic transmission - Google Patents

Abstract

PURPOSE:To prevent engine stall due to the erroneous engagement of a starting clutch at the time of reversing a vehicle by maintaining a slipping condition without permitting complete engagement even if relative rotating speed becomes below a set value when said relative rotating speed on the input and output sides of said starting clutch has a tendency to increase. CONSTITUTION:When a vehicle is operated, first, it is judged by a control circuit 60 whether a shift position is switched over from an N range to a D range and when judged yes, a duty ratio for producing a slipping condition is outputted to the solenoid 46 of a starting control valve 45 to make a starting clutch 20 a slipping condition. Then, it is judged whether the difference between the input rotating speed of the starting clutch 20 and vehicle speed, i.e., relative rotating speed has a tendency to increase and when judged no, i.e., when the vehicle is stopped or under a normal starting condition, the starting clutch 20 is shifted to starting control. When judged yes, on the other hand, since the vehicle is in a reversing condition, control is made so as to maintain a slipping control until the vehicle speed becomes zero.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for controlling a starting clutch of an automatic transmission, and more particularly to a method for controlling a slip type starting clutch that can arbitrarily control transmission torque.

Conventional technology and its problems Traditionally, automatic clutches such as fluid couplings and centrifugal clutches have been widely used as starting clutches in automatic transmissions, but fluid couplings have a large power loss during normal driving.
Furthermore, in the case of a centrifugal clutch, the transmission torque characteristics depend only on the engine speed, so a complete neutral state cannot be obtained. Furthermore, while an automatic clutch does not require external control, it is impossible to change the transmission torque characteristics and has the disadvantage that the starting characteristics are fixed.

Therefore, by using a slipping clutch such as a wet multi-disc clutch or an electromagnetic powder clutch, and by electronically controlling the transmitted torque, it achieves smooth starting performance similar to an automatic clutch, reduces power loss, and offers greater freedom in starting characteristics. A method has been proposed that achieves the expansion of

When a slip type clutch like the one above is used as a starting clutch, the neutral range (N).

When switching from P) to power range (D, L, R),
The following problems may occur: For example, if you are in N range on an uphill slope and do not press the brake pedal,
The vehicle begins to move backwards due to inertia. If you switch to D range from this state, the sensor that detects the vehicle speed cannot detect the direction of travel, so the control device will mistakenly judge that the vehicle is starting to move even though it is moving backwards, and the starting clutch will be fully engaged. This may cause the engine to stall as a result.

A similar problem can occur when switching from N range to R range on a downhill slope.

OBJECT OF THE INVENTION The present invention has been made in view of the above problems, and its purpose is to provide a starting clutch for an automatic transmission that prevents erroneous engagement of the starting clutch due to reverse movement of the vehicle and allows smooth starting at all times. The objective is to provide a control method.

Structure of the Invention In order to achieve the above object, the present invention is provided with a slip-type starting clutch that can arbitrarily control the transmission torque, and the starting clutch is activated when the relative rotational speed on the input and output sides becomes less than a set value. In an automatic transmission that is designed to be fully engaged, when the relative rotational speed on the input and output sides of the starting clutch tends to increase over time, the automatic transmission will not be fully engaged even if the relative rotational speed is below the set value. , which maintains the sliding state.

In other words, when the starting clutch is engaged and the relative rotational speed on the output side is increasing, it means that the vehicle is moving in the opposite direction.In this case, the starting clutch is engaged and the relative rotational speed on the output side is below the set value. Even if it is, the sliding state is maintained without being fully engaged. As a result, even if the vehicle speed sensor cannot detect the direction of rotation, it is possible to detect when the vehicle is moving backwards using only software, avoid engine stalling due to incorrect engagement of the starting clutch, and always achieve smooth starting.

DESCRIPTION OF EMBODIMENTS FIG. 1 shows a belt-type continuously variable transmission which is an example of an automatic transmission according to the present invention, in which a crankshaft 2 of an engine 1 is connected to an input shaft 4 via a damper mechanism 3. . An external gear 5 is fixed to the end of the input shaft 4, and this external gear 5 meshes with an internal gear 6 fixed to the drive shaft 11 of the continuously variable transmission device 0, thereby controlling the power of the input shaft 4. by decelerating the drive shaft 1
1.

The continuously variable transmission 10 includes a drive-side boob IJ provided on the drive shaft 11.
12, a driven pulley 14 provided on a driven shaft 13, and a V-belt 15 wound between both pulleys.

The drive pulley 12 has a fixed sheave 12a and a movable sheave 12.
b, and a torque cam device 16 and a compression spring 17 are provided behind the movable sheep 12b. The torque cam device 16 generates a thrust proportional to the input torque, and the compression spring 17 generates an initial thrust sufficient to prevent the V-belt 15 from loosening, and these thrusts provide the V-belt 15 with belt tension necessary for torque transmission. ing.

On the other hand, the driven pulley 14 as well as the driving pulley 12,
It has a fixed sheave 14a and a movable sheave 14b,
Behind the movable sheave 14b is a hydraulic chamber 18 for controlling the gear ratio.
is provided. The hydraulic pressure to this hydraulic chamber 18 is controlled by a pulley control valve 43, which will be described later.

A hollow shaft 19 is rotatably supported on the outer periphery of the driven shaft 13, and the driven shaft 13 and the hollow shaft 19 are connected and connected by a starting clutch 20 made of a wet multi-disc tarante. The hydraulic pressure applied to the starting clutch 20 is controlled by a starting control valve 45, which will be described later. A forward gear 21 and a reverse gear 22 are rotatably supported on the hollow shaft 19, and a forward/reverse switching dog clutch 23 connects either the forward gear 21 or the reverse gear 22 to the hollow shaft 19. It is designed to be connected. The reverse gear 2 is attached to the reverse idler shaft 24.
A reverse idler gear 25 meshing with the reverse idler gear 26 and another reverse idler gear 26 are fixed. Further, the counter shaft 27 is provided with the forward gear 21 and the reverse idler gear 26.
The counter gear 28 and the final reduction gear 2 are simultaneously engaged with the
9 is fixed, and the final reduction gear 29 meshes with the ring gear 31 of the differential mounting surface 30 to transmit power to the output shaft 32.

The pressure regulating valve 40 reduces the hydraulic pressure discharged by the oil pump 42 from the oil reservoir 41, and applies it to the pulley control valve 4 as line pressure.
3 and the start control valve 45. Pulley control valve 4
3 and the start control valve 45 control the line pressure by solenoids 44 and 46, and output control hydraulic pressure to the hydraulic chamber 18 of the driven side boolean 14 and the start clutch 20, respectively.

The concrete structure of the control valves 43 and 45 is, for example, a combination of a spool valve 47 and a solenoid valve 48 as shown in FIG.
and the drain boat 51 are selectively opened and closed, and the output boat 5
It is also possible to use a single three-point solenoid valve that outputs control hydraulic pressure to the valve 2.

The control circuit 60 receives the input rotation speed of the starting clutch 20 from the sensor 61, the rotation speed of the output shaft 32 (vehicle speed) from the sensor 62, the engine rotation speed, the throttle opening, the brake signal,
Signals such as position switch signals are input, these signals are compared and determined with data stored in advance, and control signals, such as duty control signals, are output to the solenoids 44 and 46 depending on the operating state. In particular, duty control provides an output oil pressure proportional to the duty ratio, so it is ideal for controlling the gear ratio of the continuously variable transmission 10 and controlling the transmission torque of the starting clutch 20, which require fine hydraulic control.

FIG. 4 shows an example of the transmission torque characteristic of the starting clutch 20, which, like a fluid coupling or a centrifugal clutch, has a characteristic that is approximately proportional to the square of the input rotation speed, so that smooth starting performance can be obtained. In addition, in a low rotation range near the idle rotation speed Na, low oil pressure is introduced so that the starting clutch 20 generates a predetermined transmission torque Ta for the purpose of improving responsiveness during starting and preventing shock when the clutch is engaged. It is tuned to produce a slip (creep) condition.

The transmission torque Ta at the time of slipping is adjusted to such a magnitude that the vehicle can be stopped without going backwards on an uphill slope, for example. In addition, the neutral range (P.

In the N range), no hydraulic pressure is introduced to the starting clutch 20, and the starting clutch 20 is in a completely disconnected state.

As described above, the starting clutch 20 is controlled so that the transmitted torque increases as the input rotation speed increases in accordance with the characteristics shown in FIG. (for example, 300 rpa+) or less, there is almost no shock even if the starting clutch 20 is fully engaged at that point, and the starting control can be completed in a short time. Therefore, as shown by the dashed line in FIG. 4, when the relative rotational speed on the input and output sides becomes less than the set value, the starting clutch 20 is fully engaged to complete the starting control.

By the way, in the V-belt continuously variable transmission with the above configuration,
If you do not press the brake pedal while in the N range on an uphill slope as shown in Figure 5, the vehicle will move backwards due to inertia. When switching from this state to the D range, the control circuit 60
determines whether to maintain slip control or to shift to start control based on the correlation between the input rotation speed and output rotation speed (vehicle speed) of starting clutch 20 input from sensors 61 and 62. However, since the sensor 62 that detects the vehicle speed cannot detect the direction of rotation of the output shaft 32, the control circuit 60 incorrectly determines that the vehicle is moving forward even though it is moving backwards, and the starting clutch 20 is activated to control the start. It will be moved. This increases the engagement force when the input member and output member of the starting clutch 20 are rotating in opposite directions, and especially when the rotation speed on the output side increases and
When the relative rotational speed on the output side becomes less than the set value, the starting clutch 20 is completely engaged as shown at point A in FIG. 4, resulting in a sudden increase in the load on the engine 1 and stalling of the engine.

In order to solve the above problem, the present invention implements the following method. In other words, while reversing in N range,
When switching to the range, the starting clutch 20 is initially controlled to be in a slipping state. And starting clutch 200,
The relative rotational speed on the output side is detected, and if the relative rotational speed is increasing as shown in Fig. 6, the starting clutch 20 is not immediately biased in the engaging direction, but the vehicle speed is increased until the vehicle speed reaches zero. Maintain sliding condition. Since a braking force is applied to the vehicle due to the slipping force of the starting clutch 20, the vehicle speed (when reversing) decreases, and starting control can only be started after the vehicle has come to a stop. If controlled in this way, the sensor 62
Even if the engine cannot detect the direction of rotation, engine stalling can be reliably prevented and a smooth start can always be achieved.

Next, an example of a specific control method for the starting clutch 20 will be explained with reference to FIG. 7.

When the control starts, it is first determined whether the shift position has changed from the N range to the D range (70).
, if the range has not been changed, it is determined whether the range has been changed from the N range to the R range (71), and if no change has been made, the control is terminated.

On the other hand, when either of the switching is performed, the start control valve 45
72) to generate a transmission torque corresponding to Ta in FIG. 4, for example. Next, it is necessary to determine whether the difference between the input rotation speed N of the starting clutch 20 and the vehicle speed V (converted to the rotation speed), that is, the relative rotation speed (N, -V) is on an increasing trend.73
), if the relative rotational speed is constant or decreasing, it means that the vehicle is stopped or has started normal starting, so the starting clutch 20 is shifted to starting control (75). . On the other hand, if the relative rotational speed is increasing, it means that the vehicle is moving in the opposite direction.Next, it is necessary to determine whether the vehicle speed has become O74), and if the vehicle speed has not decreased to O, then the above Slip control (72) The following controls continue. If the vehicle speed becomes O, the start clutch 20 is controlled to start in the same way as in (75), and the start is started.

The specific method of the start control (75) is as follows: input rotation speed N;
Compare the relative rotation speed (N, -V) between When the rotational speed falls below the set value, the starting clutch 20 may be fully engaged as shown at point A in FIG.

Although the above control shows the case where the N range is switched to the D or R range, the same control as above may be performed also when switching from the P range to the D or R range, for example. In other words, the P range has a reversing lock that is different from the N range, so the vehicle will not go backwards even on a slope, but if the shift lever is moving slowly, the shift lever will be locked before the D range slipping force is generated. Since there is a possibility that the vehicle will go backwards, it is meaningful to perform the control according to the present invention.

Furthermore, not only when switching from the neutral range to the power range, but also on steep slopes, the vehicle may move backwards even if the power range is maintained, so the control method of the present invention may be implemented in this case as well. good.

Furthermore, in the present invention, an electromagnetic powder clutch can be used as the starting clutch 20 instead of a wet multi-disc clutch, and in this case, the transmitted torque can be directly controlled by an electric signal, eliminating the need for a starting control valve and hydraulic pressure. The circuit can be simplified.

Furthermore, the automatic transmission of the present invention is not limited to continuously variable transmissions such as belt type continuously variable transmissions and toroidal type continuously variable transmissions, but it goes without saying that ordinary single-gear type automatic transmissions can also be used. .

Effects of the Invention As is clear from the above explanation, according to the present invention, when the relative rotational speed on the input and output sides of the starting clutch tends to increase, complete engagement is achieved even if the relative rotational speed is below the set value. Since the sliding state is maintained without causing the engine to stall, engine stalling due to incorrect engagement of the starting clutch when the vehicle is traveling in the opposite direction can be prevented, and smooth starting can always be performed. Furthermore, even if the vehicle speed sensor cannot detect the direction of rotation, the software of the control device can determine whether the vehicle is moving backwards, so existing sensors can be used.

[Brief explanation of drawings]

Figure 1 is a schematic diagram of an example of a belt-type continuously variable transmission to which the present invention is applied, Figures 2 and 3 are specific structural diagrams of a control valve,
Figure 4 is a transmission torque characteristic diagram of the starting clutch, Figure 5 is a diagram showing the reverse movement of the vehicle on a slope, Figure 6 is a diagram showing the engagement of the starting clutch and the change in output rotation speed over time, and Figure 7 is a diagram showing the actual rotation speed of the starting clutch. FIG. 2 is a flowchart diagram illustrating an example of the invention method. DESCRIPTION OF SYMBOLS 1... Engine, 4... Input shaft, 10... Continuously variable transmission, 15... V-belt, 18... Hydraulic chamber, 20
... Starting clutch, 32... Output shaft, 45... Starting control valve, 60... Control circuit.

Claims (1)

[Claims] (1) In an automatic transmission equipped with a slip-type starting clutch that can arbitrarily control the transmitted torque, the starting clutch is fully engaged when the relative rotational speed on the input and output sides falls below a set value. When the relative rotational speed on the input and output sides of the starting clutch tends to increase over time, the automatic system does not completely engage the starting clutch even if the relative rotational speed is below a set value and maintains a slipping state. How to control the starting clutch of a transmission.